Method for measuring reactor bed level from active acoustic measurement and analysis

Abstract

The present invention is a non-intrusive method to determine the fluid level in a vessel. In a preferred embodiment, the vessel is a delayed coker drum in a refinery. Waves are generated in the vessel from an outside source. For wall vibration generated in the frequency range of 1-20,000 Hz, accelerometers on the exterior wall of the vessel measures the attenuation of the vibration modes of the vessel. The fluid level can related to the attenuation of the vibration mode. For wall vibration generated in the ultrasonic range, the wave traveling in the vessel wall are guided waves. The guided wave will leak energy into the fluid inside the vessel and will attenuate depending on the fluid level. Ultrasonic receivers on the outside of the vessel measure the attenuation. The fluid level can be related attenuation of the ultrasonic waves.

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]This Application claims the benefit of U.S. Provisional Application 61 / 132,647 filed Jun. 20, 2008.[0002]This Application claims the benefit of U.S. Provisional Application 61 / 132,647 filed Jun. 20, 2008BACKGROUND OF THE INVENTION[0003]The present invention is a method to determine bed levels in a reactor. In particular, the present invention uses a non-intrusive method to monitor the bed level in the reactor in a refinery. More particularly, the method is used to monitor the fluid lever in a delayed coker drum.[0004]It is important to know the bed level in a process reactor, particularly is a delayed coker, in a refinery. Delayed-coking is an important process which is used to convert vacuum resids to lighter distillates and produce coke as byproduct. Delayed-cokers are operated in semi-batch mode, with at least two coke drums. While one is being filled or coked, the other is being de-coked. During the coking cycle, the drum is gradually ...

AI Technical Summary

Benefits of technology

[0008]The present invention is a non-intrusive method to determine the level of material in a vessel such as a process reactor, or a liquid storage tank. In a preferred embodiment, the vessel is a delayed coker drum in a refinery. The method uses an acoustic/vibration source to generate vibration or elastics waves traveling along the vessel wall. The characteristics of the wall vibration depend on the fill level of the vessel. One or more acoustic/vibration receivers are strategically placed on the exterior surface of the wall, preferably along the vertical axis of the vessel to measure the vibration response of the wall to the source. The measured vibration signals are analyzed to determine the amount of the change in the characteristics of the wall vibration due to the fill level. A correlation model describing the change in characteristic...

Problems solved by technology

Refineries that have difficulty in knowing the exact level in the drum run two risks.

This leads to significant throughput loss and maintenance cost.

The second risk is that in order to prevent the condition described above a large portion of the drum is left unfilled and unused.

This unused volume represents a loss of throughput for the unit.

This suffers from the difficulty in knowing the final density of the coke and is not reliable.

Methods using ranging radar or sonar have to be installed inside the reactor and suffer severe fouling problems.

These are more expensive, have radioactive hazards, and generally suffer from reliability issues (probably due to workers avoiding maintenance contact with radioactive devices).

Other drawbacks of the radioactive devices are that they can only provide discrete level measurements, instead of continuous measurements provided by the current invention.

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